Decoupled holographic film and diffuser

ABSTRACT

In various embodiments described herein, a display device includes a front illumination device that comprises a light guide disposed forward of an array of display elements, such as an array of interferometric modulators, to distribute light across the array of display elements. The light guide may include a turning film to deliver uniform illumination from a light source to the array of display elements. For many portable display applications, the light guide comprises the substrate used in fabricating the display elements. The display device may include additional films as well. The light guide, for example, may include a diffuser and/or an optical isolation layer to further enhance the optical characteristics of the display.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/952,941, filed on Dec. 7, 2007 and entitled “Decoupled HolographicFilm and Diffuser,” the contents of which is hereby incorporated byreference in their entirety.

BACKGROUND

1. Field

The present invention relates to microelectromechanical systems (MEMS).

2. Description of the Related Art

Microelectromechanical systems (MEMS) include micro mechanical elements,actuators, and electronics. Micromechanical elements may be createdusing deposition, etching, and/or other micromachining processes thatetch away parts of substrates and/or deposited material layers or thatadd layers to form electrical and electromechanical devices. One type ofMEMS device is called an interferometric modulator. As used herein, theterm interferometric modulator or interferometric light modulator refersto a device that selectively absorbs and/or reflects light using theprinciples of optical interference. In certain embodiments, aninterferometric modulator may comprise a pair of conductive plates, oneor both of which may be transparent and/or reflective in whole or partand capable of relative motion upon application of an appropriateelectrical signal. In a particular embodiment, one plate may comprise astationary layer deposited on a substrate and the other plate maycomprise a metallic membrane separated from the stationary layer by anair gap. As described herein in more detail, the position of one platein relation to another can change the optical interference of lightincident on the interferometric modulator. Such devices have a widerange of applications, and it would be beneficial in the art to utilizeand/or modify the characteristics of these types of devices so thattheir features can be exploited in improving existing products andcreating new products that have not yet been developed.

SUMMARY

Various embodiments described herein comprise a display devicecomprising a substrate, a plurality of display elements, a turning film,and a cladding. The substrate is configured to guide light therein. Theplurality of display elements is supported by the substrate and isrearward of the substrate. The turning film is forward the substrate andis configured to turn light guided in the substrate toward the pluralityof display elements. The plurality of scattering features are forwardthe turning film. The cladding is disposed between the turning film andthe scattering features such that light is guided in the turning filmand the substrate.

Certain embodiments described herein comprise a display devicecomprising means for displaying an image and means for supporting thedisplaying means. The supporting means is disposed forward thedisplaying means and is configured to guide light therein. The displaydevice further comprises means for turning light guided within thesupporting means toward the displaying means. The light turning means isforward of the supporting means. The display device additionallycomprises means for scattering light, which is disposed forward of thelight turning means. The display device also comprises means forredirecting light from the light turning means back into the lightturning means such that light is guided in the light turning means andthe supporting means. The light redirecting means is between the lightturning means and the light scattering means.

Certain embodiments described herein comprise a method of manufacturinga display device that comprises providing a substrate with plurality ofdisplay elements rearward the substrate. The substrate is configured toguide light therein. In this method, a turning film is disposed forwardthe substrate. The turning film is configured to turn light guided inthe substrate and the turning film toward the plurality of displayelements. A plurality of scattering features are provided forward theturning film. A cladding is disposed between the turning film and thescattering features such that light is guided in the light turning filmand the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view depicting a portion of one embodiment of aninterferometric modulator display in which a movable reflective layer ofa first interferometric modulator is in a relaxed position and a movablereflective layer of a second interferometric modulator is in an actuatedposition.

FIG. 2 is a system block diagram illustrating one embodiment of anelectronic device incorporating a 3×3 interferometric modulator display.

FIG. 3 is a diagram of movable mirror position versus applied voltagefor one exemplary embodiment of an interferometric modulator of FIG. 1.

FIG. 4 is an illustration of a set of row and column voltages that maybe used to drive an interferometric modulator display.

FIG. 5A illustrates one exemplary frame of display data in the 3×3interferometric modulator display of FIG. 2.

FIG. 5B illustrates one exemplary timing diagram for row and columnsignals that may be used to write the frame of FIG. 5A.

FIGS. 6A and 6B are system block diagrams illustrating an embodiment ofa visual display device comprising a plurality of interferometricmodulators.

FIG. 7A is a cross section of the device of FIG. 1.

FIG. 7B is a cross section of an alternative embodiment of aninterferometric modulator.

FIG. 7C is a cross section of another alternative embodiment of aninterferometric modulator.

FIG. 7D is a cross section of yet another alternative embodiment of aninterferometric modulator.

FIG. 7E is a cross section of an additional alternative embodiment of aninterferometric modulator.

FIG. 8 is a cross section of a portion of a display device comprising aturning film and a diffuser disposed on a substrate on which displayelements are formed.

FIG. 9 is a cross section of a portion of a display device furthercomprising an anti-reflective coating.

FIG. 10 is a cross section of a portion of a display device furthercomprising a lens or a touch panel.

DETAILED DESCRIPTION OF THE CERTAIN PREFERRED EMBODIMENTS

The following detailed description is directed to certain specificembodiments of the invention. However, the invention can be embodied ina multitude of different ways. In this description, reference is made tothe drawings wherein like parts are designated with like numeralsthroughout. As will be apparent from the following description, theembodiments may be implemented in any device that is configured todisplay an image, whether in motion (e.g., video) or stationary (e.g.,still image), and whether textual or pictorial. More particularly, it iscontemplated that the embodiments may be implemented in or associatedwith a variety of electronic devices such as, but not limited to, mobiletelephones, wireless devices, personal data assistants (PDAs), hand-heldor portable computers, GPS receivers/navigators, cameras, MP3 players,camcorders, game consoles, wrist watches, clocks, calculators,television monitors, flat panel displays, computer monitors, autodisplays (e.g., odometer display, etc.), cockpit controls and/ordisplays, display of camera views (e.g., display of a rear view camerain a vehicle), electronic photographs, electronic billboards or signs,projectors, architectural structures, packaging, and aestheticstructures (e.g., display of images on a piece of jewelry). MEMS devicesof similar structure to those described herein can also be used innon-display applications such as in electronic switching devices.

In various embodiments described herein, the display device includes afront illumination device that comprises a light guide disposed forwardof an array of display elements, such as an array of interferometricmodulators, to distribute light across the array of display elements.For example, a light guide that includes a turning film may be disposedin front of the array of display elements to deliver uniformillumination from a light source to the array of display elements whileallowing for the option of illumination from ambient lighting of thearray of display elements. For many portable display applications,however, it is important that the display be very thin. Accordingly, invarious embodiments described herein, the light guide comprises thesubstrate used in fabricating the display elements. The light guide mayinclude additional films as well. The light guide, for example, mayinclude a turning film deposited or laminated on the top or bottomsurface of the glass substrate supporting the array of display elements.As a consequence, the overall thickness of the entire display is onlyslightly increased beyond that of the display elements themselves whichare formed on a substrate. Certain embodiments include additionaloptical layers, such as a diffuser and/or an optical isolation layer tofurther enhance the optical characteristics of the display.

One interferometric modulator display embodiment comprising aninterferometric MEMS display element is illustrated in FIG. 1. In thesedevices, the pixels are in either a bright or dark state. In the bright(“on” or “open”) state, the display element reflects a large portion ofincident visible light to a user. When in the dark (“off” or “closed”)state, the display element reflects little incident visible light to theuser. Depending on the embodiment, the light reflectance properties ofthe “on” and “off” states may be reversed. MEMS pixels can be configuredto reflect predominantly at selected colors, allowing for a colordisplay in addition to black and white.

FIG. 1 is an isometric view depicting two adjacent pixels in a series ofpixels of a visual display, wherein each pixel comprises a MEMSinterferometric modulator. In some embodiments, an interferometricmodulator display comprises a row/column array of these interferometricmodulators. Each interferometric modulator includes a pair of reflectivelayers positioned at a variable and controllable distance from eachother to form a resonant optical gap with at least one variabledimension. In one embodiment, one of the reflective layers may be movedbetween two positions. In the first position, referred to herein as therelaxed position, the movable reflective layer is positioned at arelatively large distance from a fixed partially reflective layer. Inthe second position, referred to herein as the actuated position, themovable reflective layer is positioned more closely adjacent to thepartially reflective layer. Incident light that reflects from the twolayers interferes constructively or destructively depending on theposition of the movable reflective layer, producing either an overallreflective or non-reflective state for each pixel.

The depicted portion of the pixel array in FIG. 1 includes two adjacentinterferometric modulators 12 a and 12 b. In the interferometricmodulator 12 a on the left, a movable reflective layer 14 a isillustrated in a relaxed position at a predetermined distance from anoptical stack 16 a, which includes a partially reflective layer. In theinterferometric modulator 12 b on the right, the movable reflectivelayer 14 b is illustrated in an actuated position adjacent to theoptical stack 16 b.

The optical stacks 16 a and 16 b (collectively referred to as opticalstack 16), as referenced herein, typically comprise several fusedlayers, which can include an electrode layer, such as indium tin oxide(ITO), a partially reflective layer, such as chromium, and a transparentdielectric. The optical stack 16 is thus electrically conductive,partially transparent, and partially reflective, and may be fabricated,for example, by depositing one or more of the above layers onto atransparent substrate 20. The partially reflective layer can be formedfrom a variety of materials that are partially reflective such asvarious metals, semiconductors, and dielectrics. The partiallyreflective layer can be formed of one or more layers of materials, andeach of the layers can be formed of a single material or a combinationof materials.

In some embodiments, the layers of the optical stack 16 are patternedinto parallel strips, and may form row electrodes in a display device asdescribed further below. The movable reflective layers 14 a, 14 b may beformed as a series of parallel strips of a deposited metal layer orlayers (orthogonal to the row electrodes of 16 a, 16 b) deposited on topof posts 18 and an intervening sacrificial material deposited betweenthe posts 18. When the sacrificial material is etched away, the movablereflective layers 14 a, 14 b are separated from the optical stacks 16 a,16 b by a defined gap 19. A highly conductive and reflective materialsuch as aluminum may be used for the reflective layers 14, and thesestrips may form column electrodes in a display device.

With no applied voltage, the gap 19 remains between the movablereflective layer 14 a and optical stack 16 a, with the movablereflective layer 14 a in a mechanically relaxed state, as illustrated bythe pixel 12 a in FIG. 1. However, when a potential difference isapplied to a selected row and column, the capacitor formed at theintersection of the row and column electrodes at the corresponding pixelbecomes charged, and electrostatic forces pull the electrodes together.If the voltage is high enough, the movable reflective layer 14 isdeformed and is forced against the optical stack 16. A dielectric layer(not illustrated in this Figure) within the optical stack 16 may preventshorting and control the separation distance between layers 14 and 16,as illustrated by pixel 12 b on the right in FIG. 1. The behavior is thesame regardless of the polarity of the applied potential difference. Inthis way, row/column actuation that can control the reflective vs.non-reflective pixel states is analogous in many ways to that used inconventional LCD and other display technologies.

FIGS. 2 through 5B illustrate one exemplary process and system for usingan array of interferometric modulators in a display application.

FIG. 2 is a system block diagram illustrating one embodiment of anelectronic device that may incorporate aspects of the invention. In theexemplary embodiment, the electronic device includes a processor 21which may be any general purpose single- or multi-chip microprocessorsuch as an ARM, Pentium®, Pentium II®, Pentium III®, Pentium IV®,Pentium® Pro, an 8051, a MIPS®, a Power PC®, an ALPHA®, or any specialpurpose microprocessor such as a digital signal processor,microcontroller, or a programmable gate array. As is conventional in theart, the processor 21 may be configured to execute one or more softwaremodules. In addition to executing an operating system, the processor maybe configured to execute one or more software applications, including aweb browser, a telephone application, an email program, or any othersoftware application.

In one embodiment, the processor 21 is also configured to communicatewith an array driver 22. In one embodiment, the array driver 22 includesa row driver circuit 24 and a column driver circuit 26 that providesignals to a display array or panel 30. The cross section of the arrayillustrated in FIG. 1 is shown by the lines 1-1 in FIG. 2. For MEMSinterferometric modulators, the row/column actuation protocol may takeadvantage of a hysteresis property of these devices illustrated in FIG.3. It may require, for example, a 10 volt potential difference to causea movable layer to deform from the relaxed state to the actuated state.However, when the voltage is reduced from that value, the movable layermaintains its state as the voltage drops back below 10 volts. In theexemplary embodiment of FIG. 3, the movable layer does not relaxcompletely until the voltage drops below 2 volts. Thus, there exists awindow of applied voltage, about 3 to 7 V in the example illustrated inFIG. 3, within which the device is stable in either the relaxed oractuated state. This is referred to herein as the “hysteresis window” or“stability window.” For a display array having the hysteresischaracteristics of FIG. 3, the row/column actuation protocol can bedesigned such that during row strobing, pixels in the strobed row thatare to be actuated are exposed to a voltage difference of about 10volts, and pixels that are to be relaxed are exposed to a voltagedifference of close to zero volts. After the strobe, the pixels areexposed to a steady state voltage difference of about 5 volts such thatthey remain in whatever state the row strobe put them in. After beingwritten, each pixel sees a potential difference within the “stabilitywindow” of 3-7 volts in this example. This feature makes the pixeldesign illustrated in FIG. 1 stable under the same applied voltageconditions in either an actuated or relaxed pre-existing state. Sinceeach pixel of the interferometric modulator, whether in the actuated orrelaxed state, is essentially a capacitor formed by the fixed and movingreflective layers, this stable state can be held at a voltage within thehysteresis window with almost no power dissipation. Essentially nocurrent flows into the pixel if the applied potential is fixed.

In typical applications, a display frame may be created by asserting theset of column electrodes in accordance with the desired set of actuatedpixels in the first row. A row pulse is then applied to the row 1electrode, actuating the pixels corresponding to the asserted columnlines. The asserted set of column electrodes is then changed tocorrespond to the desired set of actuated pixels in the second row. Apulse is then applied to the row 2 electrode, actuating the appropriatepixels in row 2 in accordance with the asserted column electrodes. Therow 1 pixels are unaffected by the row 2 pulse, and remain in the statethey were set to during the row 1 pulse. This may be repeated for theentire series of rows in a sequential fashion to produce the frame.Generally, the frames are refreshed and/or updated with new display databy continually repeating this process at some desired number of framesper second. A wide variety of protocols for driving row and columnelectrodes of pixel arrays to produce display frames are also well knownand may be used in conjunction with the present invention.

FIGS. 4, 5A, and 5B illustrate one possible actuation protocol forcreating a display frame on the 3×3 array of FIG. 2. FIG. 4 illustratesa possible set of column and row voltage levels that may be used forpixels exhibiting the hysteresis curves of FIG. 3. In the FIG. 4embodiment, actuating a pixel involves setting the appropriate column to−V_(bias), and the appropriate row to +ΔV, which may correspond to −5volts and +5 volts, respectively Relaxing the pixel is accomplished bysetting the appropriate column to +V_(bias), and the appropriate row tothe same +ΔV, producing a zero volt potential difference across thepixel. In those rows where the row voltage is held at zero volts, thepixels are stable in whatever state they were originally in, regardlessof whether the column is at +V_(bias), or −V_(bias). As is alsoillustrated in FIG. 4, it will be appreciated that voltages of oppositepolarity than those described above can be used, e.g., actuating a pixelcan involve setting the appropriate column to +V_(bias), and theappropriate row to −ΔV. In this embodiment, releasing the pixel isaccomplished by setting the appropriate column to −V_(bias), and theappropriate row to the same −ΔV, producing a zero volt potentialdifference across the pixel.

FIG. 5B is a timing diagram showing a series of row and column signalsapplied to the 3×3 array of FIG. 2 which will result in the displayarrangement illustrated in FIG. 5A, where actuated pixels arenon-reflective. Prior to writing the frame illustrated in FIG. 5A, thepixels can be in any state, and in this example, all the rows are at 0volts, and all the columns are at +5 volts. With these applied voltages,all pixels are stable in their existing actuated or relaxed states.

In the FIG. 5A frame, pixels (1,1), (1,2), (2,2), (3,2) and (3,3) areactuated. To accomplish this, during a “line time” for row 1, columns 1and 2 are set to −5 volts, and column 3 is set to +5 volts. This doesnot change the state of any pixels, because all the pixels remain in the3-7 volt stability window. Row 1 is then strobed with a pulse that goesfrom 0, up to 5 volts, and back to zero. This actuates the (1,1) and(1,2) pixels and relaxes the (1,3) pixel. No other pixels in the arrayare affected. To set row 2 as desired, column 2 is set to −5 volts, andcolumns 1 and 3 are set to +5 volts. The same strobe applied to row 2will then actuate pixel (2,2) and relax pixels (2,1) and (2,3). Again,no other pixels of the array are affected. Row 3 is similarly set bysetting columns 2 and 3 to −5 volts, and column 1 to +5 volts. The row 3strobe sets the row 3 pixels as shown in FIG. 5A. After writing theframe, the row potentials are zero, and the column potentials can remainat either +5 or −5 volts, and the display is then stable in thearrangement of FIG. 5A. It will be appreciated that the same procedurecan be employed for arrays of dozens or hundreds of rows and columns. Itwill also be appreciated that the timing, sequence, and levels ofvoltages used to perform row and column actuation can be varied widelywithin the general principles outlined above, and the above example isexemplary only, and any actuation voltage method can be used with thesystems and methods described herein.

FIGS. 6A and 6B are system block diagrams illustrating an embodiment ofa display device 40. The display device 40 can be, for example, acellular or mobile telephone. However, the same components of displaydevice 40 or slight variations thereof are also illustrative of varioustypes of display devices such as televisions and portable media players.

The display device 40 includes a housing 41, a display 30, an antenna43, a speaker 45, an input device 48, and a microphone 46. The housing41 is generally formed from any of a variety of manufacturing processesas are well known to those of skill in the art, including injectionmolding and vacuum forming. In addition, the housing 41 may be made fromany of a variety of materials, including, but not limited to, plastic,metal, glass, rubber, and ceramic, or a combination thereof. In oneembodiment, the housing 41 includes removable portions (not shown) thatmay be interchanged with other removable portions of different color, orcontaining different logos, pictures, or symbols.

The display 30 of exemplary display device 40 may be any of a variety ofdisplays, including a bi-stable display, as described herein. In otherembodiments, the display 30 includes a flat-panel display, such asplasma, EL, OLED, STN LCD, or TFT LCD as described above, or anon-flat-panel display, such as a CRT or other tube device, as is wellknown to those of skill in the art. However, for purposes of describingthe present embodiment, the display 30 includes an interferometricmodulator display, as described herein.

The components of one embodiment of exemplary display device 40 areschematically illustrated in FIG. 6B. The illustrated exemplary displaydevice 40 includes a housing 41 and can include additional components atleast partially enclosed therein. For example, in one embodiment, theexemplary display device 40 includes a network interface 27 thatincludes an antenna 43, which is coupled to a transceiver 47. Thetransceiver 47 is connected to a processor 21, which is connected toconditioning hardware 52. The conditioning hardware 52 may be configuredto condition a signal (e.g., filter a signal). The conditioning hardware52 is connected to a speaker 45 and a microphone 46. The processor 21 isalso connected to an input device 48 and a driver controller 29. Thedriver controller 29 is coupled to a frame buffer 28 and to an arraydriver 22, which in turn is coupled to a display array 30. A powersupply 50 provides power to all components as required by the particularexemplary display device 40 design.

The network interface 27 includes the antenna 43 and the transceiver 47so that the exemplary display device 40 can communicate with one or moredevices over a network. In one embodiment, the network interface 27 mayalso have some processing capabilities to relieve requirements of theprocessor 21. The antenna 43 is any antenna known to those of skill inthe art for transmitting and receiving signals. In one embodiment, theantenna transmits and receives RF signals according to the IEEE 802.11standard, including IEEE 802.11(a), (b), or (g). In another embodiment,the antenna transmits and receives RF signals according to the BLUETOOTHstandard. In the case of a cellular telephone, the antenna is designedto receive CDMA, GSM, AMPS, or other known signals that are used tocommunicate within a wireless cell phone network. The transceiver 47pre-processes the signals received from the antenna 43 so that they maybe received by and further manipulated by the processor 21. Thetransceiver 47 also processes signals received from the processor 21 sothat they may be transmitted from the exemplary display device 40 viathe antenna 43.

In an alternative embodiment, the transceiver 47 can be replaced by areceiver. In yet another alternative embodiment, network interface 27can be replaced by an image source, which can store or generate imagedata to be sent to the processor 21. For example, the image source canbe a digital video disc (DVD) or a hard-disc drive that contains imagedata, or a software module that generates image data.

Processor 21 generally controls the overall operation of the exemplarydisplay device 40. The processor 21 receives data, such as compressedimage data from the network interface 27 or an image source, andprocesses the data into raw image data or into a format that is readilyprocessed into raw image data. The processor 21 then sends the processeddata to the driver controller 29 or to frame buffer 28 for storage. Rawdata typically refers to the information that identifies the imagecharacteristics at each location within an image. For example, suchimage characteristics can include color, saturation, and gray-scalelevel.

In one embodiment, the processor 21 includes a microcontroller, CPU, orlogic unit to control operation of the exemplary display device 40.Conditioning hardware 52 generally includes amplifiers and filters fortransmitting signals to the speaker 45, and for receiving signals fromthe microphone 46. Conditioning hardware 52 may be discrete componentswithin the exemplary display device 40, or may be incorporated withinthe processor 21 or other components.

The driver controller 29 takes the raw image data generated by theprocessor 21 either directly from the processor 21 or from the framebuffer 28 and reformats the raw image data appropriately for high speedtransmission to the array driver 22. Specifically, the driver controller29 reformats the raw image data into a data flow having a raster-likeformat, such that it has a time order suitable for scanning across thedisplay array 30. Then the driver controller 29 sends the formattedinformation to the array driver 22. Although a driver controller 29,such as a LCD controller, is often associated with the system processor21 as a stand-alone Integrated Circuit (IC), such controllers may beimplemented in many ways. They may be embedded in the processor 21 ashardware, embedded in the processor 21 as software, or fully integratedin hardware with the array driver 22.

Typically, the array driver 22 receives the formatted information fromthe driver controller 29 and reformats the video data into a parallelset of waveforms that are applied many times per second to the hundredsand sometimes thousands of leads coming from the display's x-y matrix ofpixels.

In one embodiment, the driver controller 29, array driver 22, anddisplay array 30 are appropriate for any of the types of displaysdescribed herein. For example, in one embodiment, driver controller 29is a conventional display controller or a bi-stable display controller(e.g., an interferometric modulator controller). In another embodiment,array driver 22 is a conventional driver or a bi-stable display driver(e.g., an interferometric modulator display). In one embodiment, adriver controller 29 is integrated with the array driver 22. Such anembodiment is common in highly integrated systems such as cellularphones, watches, and other small area displays. In yet anotherembodiment, display array 30 is a typical display array or a bi-stabledisplay array (e.g., a display including an array of interferometricmodulators).

The input device 48 allows a user to control the operation of theexemplary display device 40. In one embodiment, input device 48 includesa keypad, such as a QWERTY keyboard or a telephone keypad, a button, aswitch, a touch-sensitive screen, or a pressure- or heat-sensitivemembrane. In one embodiment, the microphone 46 is an input device forthe exemplary display device 40. When the microphone 46 is used to inputdata to the device, voice commands may be provided by a user forcontrolling operations of the exemplary display device 40.

Power supply 50 can include a variety of energy storage devices as arewell known in the art. For example, in one embodiment, power supply 50is a rechargeable battery, such as a nickel-cadmium battery or a lithiumion battery. In another embodiment, power supply 50 is a renewableenergy source, a capacitor, or a solar cell including a plastic solarcell, and solar-cell paint. In another embodiment, power supply 50 isconfigured to receive power from a wall outlet.

In some embodiments, control programmability resides, as describedabove, in a driver controller which can be located in several places inthe electronic display system. In some embodiments, controlprogrammability resides in the array driver 22. Those of skill in theart will recognize that the above-described optimizations may beimplemented in any number of hardware and/or software components and invarious configurations.

The details of the structure of interferometric modulators that operatein accordance with the principles set forth above may vary widely. Forexample, FIGS. 7A-7E illustrate five different embodiments of themovable reflective layer 14 and it's supporting structures. FIG. 7A is across section of the embodiment of FIG. 1, where a strip of metalmaterial 14 is deposited on orthogonally extending supports 18. In FIG.7B, the moveable reflective layer 14 is attached to supports at thecorners only, on tethers 32. In FIG. 7C, the moveable reflective layer14 is suspended from a deformable layer 34, which may comprise aflexible metal. The deformable layer 34 connects, directly orindirectly, to the substrate 20 around the perimeter of the deformablelayer 34. These connections are herein referred to as support posts. Theembodiment illustrated in FIG. 7D has support post plugs 42 upon whichthe deformable layer 34 rests. The movable reflective layer 14 remainssuspended over the gap, as in FIGS. 7A-7C, but the deformable layer 34does not form the support posts by filling holes between the deformablelayer 34 and the optical stack 16. Rather, the support posts are formedof a planarization material, which is used to form support post plugs42. The embodiment illustrated in FIG. 7E is based on the embodimentshown in FIG. 7D, but may also be adapted to work with any of theembodiments illustrated in FIGS. 7A-7C, as well as additionalembodiments not shown. In the embodiment shown in FIG. 7E, an extralayer of metal or other conductive material has been used to form a busstructure 44. This allows signal routing along the back of theinterferometric modulators, eliminating a number of electrodes that mayotherwise have had to be formed on the substrate 20.

In embodiments such as those shown in FIG. 7, the interferometricmodulators function as direct-view devices, in which images are viewedfrom the front side of the transparent substrate 20, the side oppositeto that upon which the modulator is arranged. In these embodiments, thereflective layer 14 optically shields the portions of theinterferometric modulator on the side of the reflective layer oppositethe substrate 20, including the deformable layer 34. This allows theshielded areas to be configured and operated upon without negativelyaffecting the image quality. Such shielding allows the bus structure 44in FIG. 7E, which provides the ability to separate the opticalproperties of the modulator from the electromechanical properties of themodulator, such as addressing and the movements that result from thataddressing. This separable modulator architecture allows the structuraldesign and materials used for the electromechanical aspects and theoptical aspects of the modulator to be selected and to functionindependently of each other. Moreover, the embodiments shown in FIGS.7C-7E have additional benefits deriving from the decoupling of theoptical properties of the reflective layer 14 from its mechanicalproperties, which are carried out by the deformable layer 34. Thisallows the structural design and materials used for the reflective layer14 to be optimized with respect to the optical properties, and thestructural design and materials used for the deformable layer 34 to beoptimized with respect to desired mechanical properties.

As described above, in certain embodiments the interferometricmodulators are reflective and rely on ambient lighting in daylight orwell-lit environments. In addition, an artificial source of illuminationcan be provided for illumination of interferometric modulators in darkambient environments. The illumination source for interferometricmodulator displays may, for example, comprise a front light that uses alight guide to collect light through a narrow rectangular edge of thelight guide and redirect it towards the interferometric modulators. Incertain embodiments, the light guide may comprise a plastic or glassslab, sheet, plate, or film that is disposed in front of theinterferometric modulators. A turning film may be laminated to ordeposited on the slab, sheet, or film to redirect light propagatingalong the light guide toward the display elements. In various designs,such light guides comprise a layer of plastic approximately 1 mm thick.However, for certain applications, the light guide might have a reducedor minimal thickness, for example, of less than about one-half amillimeter, to keep the overall display device thin.

One way to reduce or minimize the overall thickness of the display is toincorporate the turning film on a structural component of theinterferometric modulators, such as the substrate on which theinterferometric modulators are formed. This substrate may compriseglass. Alternatively, the substrate may comprise plastic or anothersubstantially optically transmissive material. By applying the turningfilm on a structural component of the interferometric modulators, suchas the glass substrate, the light from the artificial light source canbe coupled into the glass substrate layer of the interferometricmodulators and turned toward the interferometric modulators by theturning film. In such embodiments, the separate glass or plastic slab,sheet, or film is not used and thus the thickness of the overall displaydevice can be significantly reduced.

In certain embodiments, one or more additional optical layers, such as adiffuser or an optical isolation layer may also be disposed on thesubstrate of the interferometric modulators to otherwise improve theoptical performance of the display. For example, a diffuser layer may beprovided to scatter light reflected from the interferometric modulatorsproviding a more diffuse look to the display which may otherwise be toomirror-like. Alternatively or in addition, an optical isolation layermay be provided between the light guiding portion of the display and theinterferometric modulators to prevent the interferometric modulatorsfrom absorbing light propagating through the light guiding portion. Asdescribed herein, the geometric arrangement of the turning film,diffuser, and additional optical films on the substrate relative to theinterferometric modulator may be selected to enhance the efficiency ofthe light guiding portion of the display, to further enhance the opticalperformance of the overall display, or provide other advantages.

The display device may be formed using any of a variety of manufacturingprocesses known to those skilled in the art to adhere one or more of theoptical layers described herein on the glass or plastic substrate of thearray of display elements. The glass or plastic substrate comprises asupport layer upon which the display elements, such as an array ofinterferometric modulators, are fabricated. As disclosed herein, thesubstrate may be further used to support one or more optical layers ofthe display device.

In one embodiment, a turning film may be deposited or laminated to thesubstrate. For example, the turning film may be laminated to a topsurface of substrate using a pressure sensitive adhesive. Alternatively,the turning film may be deposited on the substrate using techniquesknown in the art or other techniques yet to be developed. The turningfilm may be disposed on the opposite surface of the substrate from thearray of display elements. In certain embodiments, one or more layersmay be disposed between the turning film and the substrate.

A diffuser may also be adhered to the glass substrate. In someembodiments, the diffuser is disposed forward of the turning film suchthat the turning film is between the diffuser and the substrate. Forexample, the diffuser may be disposed on the turning film. In someembodiments, one or more layers may be disposed between the diffuser andthe turning film. The diffuser may be coated, deposited, laminated, oretched on the turning film or another layer between the diffuser and theturning film using any suitable techniques known in the art or yet to bedeveloped. For example, the diffuser may be spin cast, or alternativelythe diffuser may comprise a thin film grown directly on the surface ofthe turning film or another layer disposed over the turning film. Insome embodiments the diffuser comprises adhesive with particulatestherein for scattering, for example, a pressure-sensitive adhesive withdiffusing features, used to laminate one or more layers or structures tothe turning film. In other embodiments, the diffuser may be a surfacediffuser sheet or a volume diffuser sheet laminated to the turning filmor a layer over the turning film. The diffuser may also comprise a thinfilm formed on a carrier.

In certain embodiments, an optical isolation layer may be disposedbetween the glass substrate and the array of display elements. Forexample, the optical isolation layer may be laminated to or deposited onthe surface of the substrate between the glass substrate and the arrayof display elements. In other embodiments, the optical isolation layermay be laminated to or deposited on a layer over the substrate such thatthe optical isolation layer is between the glass substrate and the arrayof display elements.

Moreover, a wide variety of variation is possible. Films, layers,components, and/or elements may be added, removed, or rearranged.Additionally, processing steps may be added, removed, or reordered.Also, although the terms film and layer have been used herein, suchterms as used herein include film stacks and multilayers. Such filmstacks and multilayers may be adhered to other structures using adhesiveor may be formed on other structures using deposition techniques or inother manners. Thus, it is apparent that any one of several geometricarrangements of the multiple optical layers can be produced on thesubstrate of the display elements using known manufacturing techniquesor techniques yet to be developed to provide a thin display devicehaving certain desired optical characteristics.

FIG. 8 illustrates one embodiment of a portion of an illuminationapparatus 80 in which a turning film 82 is deposited on a top surface ofa glass substrate 85 for an array of interferometric modulators 86. Inthe embodiment shown in FIG. 8, the turning film 82 includes turningfeatures 82 a disposed on a carrier 82 b. Although in the embodimentshown in FIG. 8, the turning features 82 a are rearward of the carrier82 b, in other embodiments the turning features are forward of thecarrier. In still other embodiments, the carrier 82 b is excluded. Theturning film 82 may be adhered to the glass substrate 85 using anadhesive such as a pressure sensitive adhesive in some embodiments.

The glass substrate 85 and turning film 82 form a light guiding region81 of the illumination apparatus 80 through which light can be guided.However, the overall thickness of the display device due to the lightguide 81 is only increased by the addition of the turning film 82, sincethe glass substrate 85 is a structural component of the interferometricmodulators 86. The need for a separate glass or plastic slab or sheetfor the light guide 81 has been eliminated by adhering the turning film82 directly to the glass substrate 85 of the interferometric modulators86 and using the substrate to guide light. Consequently, the overallthickness of the illumination apparatus 80 is only increased by thethickness of the turning film 82, which is generally between about50-300 microns. A pressure sensitive adhesive between the turning film82 and the substrate 85 may be about 25-50 microns in some embodiments.

The embodiment shown in FIG. 8 further comprises a diffuser 84 disposedover the light guide 81 and array of interferometric modulators 86. Thediffuser 84 comprises a plurality of diffusing or scatter features 84 adisposed on a carrier 84 b. Although the plurality of scatter features84 a are shown disposed in a portion of the diffuser rearward of thecarrier 84 b, in other embodiments the plurality of scatter features 84a may be disposed in a portion of the diffuser forward of the carrier 84b. Alternatively, the carrier may be excluded. The diffuser 84 ispositioned forward of and adhered to the turning layer 82 such that theturning layer is between the diffuser and the substrate 85 andinterferometric modulators 86.

A light source 83 comprising for example one or more light emittingdiodes (LEDs) is disposed with respect to the light guide 81 to injectlight therein. In the embodiment shown in FIG. 8, for example, the light5 from the light source 83 is injected in to an edge of the lightguiding portion 81 of the illumination apparatus 80. In someembodiments, the light source 83 comprises a light injection system thattransforms light from a point source emitter (e.g., a light emittingdiode) into a line source. This light injection system may, for example,comprise a light bar. Other types of light sources may also be used.

Thus, light 5 is injected into the edge of the turning film 82 and/orthe glass substrate 85. The light 5 is propagated along the lightguiding region 81 at least in part through total internal reflection dueto the difference in index of refraction between the turning film 82 andthe diffuser 84.

For example, the turning film 82 and/or carrier 82 b typically comprisesa material such as polycarbonate, acrylic such as polymethymethacrylate(PMMA), or acrylate copolymers such as poly(styrene-methylmethacrylate)polymers (PS-PMMA, sold under the name of Zylar), or other opticallytransparent plastics. The index of refraction of polycarbonate isapproximately 1.59 and for Zylar is approximately 1.54 for wavelengthsin the visible spectrum.

The diffuser 84 may comprise material having a lower refractive index.This material may for example comprise pressure sensitive adhesivehaving an index of refraction of 1.47. This material is referred toherein as a cladding 88 a since this material facilitates guiding oflight within the light guide region 81 via total internal reflection. Inparticular, since the index of refraction of the turning film 82 isgreater than that of cladding 88 a, light incident on the turningfilm/cladding interface at an angle greater than the critical angle willbe reflected back into the light guiding region 81 and will continue topropagate along the light guiding region 81.

The light 5 may also reflect from the display elements 86 additionallysupporting propagation of the light along the light guide 81. Thedisplay elements 86, such as interferometric modulators, may however, beabsorbing and thus may absorb some of the light incident thereon as isdiscussed more fully below.

Accordingly, the display device may further comprise an opticalisolation layer 88 b disposed between the glass substrate 85 and thearray of interferometric modulators 86. Typically, the interferometricmodulators 86 are absorptive structures, for light rays guided at anangle of 45-90 degrees measured from the normal to the display elements.Thus, some of the light propagating through the light guiding portion 81and incident on the interferometric modulators 86 at an oblique anglemay be substantially absorbed by the interferometric modulators 86 aftera sufficient number of reflections. In order to reduce, minimize, orprevent this loss of light due to absorption, the optical isolationlayer 88 b may be disposed between the glass substrate 85 and theinterferometric modulators 86. The optical isolation layer 88 b, asdiscussed in more detail below, advantageously has an index ofrefraction substantially lower than the glass substrate 85, such thatlight traveling through the light guiding potion 81 and striking theglass/optical isolation film interface at an oblique or grazing angle,for example, greater than the critical angle (e.g., greater than 40° or50°), will be totally internally reflected back into the light guidingportion 81 of the illumination apparatus 80. In various embodiments, theoptical isolation layer comprises silicon dioxide, or fluorinatedsilicon dioxide. Other materials may be employed as well.

In certain embodiments, the indices of refraction of the multipleoptical layers comprising the light guiding portion 81, here the turningfilm 82 and the glass substrate 85, are advantageously close such thatlight may be transmitted through the multiple optical layers withoutbeing substantially reflected or refracted. The substrate 85 may forexample have an index of refraction of 1.52. As described above, thesubstrate 85 may comprise glass or polymeric material in certainembodiments.

In some embodiments, the refractive index of substrate 85 is lower thanthat of turning film 82. With such a design, some portion of the lightincident at large incident angles (e.g. 70° to 90°) on the interfacebetween substrate 85 and the turning features 82 a would be reflectedback such that light is guided to the end of the turning film 82opposite the light source 83. Such a configuration may improve theuniformity of the distribution of light directed onto the displayelements 86, for example, when the efficiency of the turning film 82 ishigh.

In certain embodiments, the light guiding portion 81 or other portionsof the illumination apparatus 80 further comprises an adhesive such aspressure sensitive adhesive (PSA) layer. The PSA layer may be used toadhere the diffuser layer 84, the turning film 82, and the glasssubstrate 85. In various embodiments, the PSA layers are transparentwith an index of refraction of between about 1.47-1.53 such that theindex of refraction matches the index of refraction of glass substrate85, generally about 1.52 for wavelengths in the visible spectrum. Forexample, in certain embodiments, the index of refraction of the PSAlayers is about 1.53. Matching the indices of refraction of the PSAlayers with the glass substrate 85 and the turning film 82 isadvantageous in preventing unwanted reflections originating from theambient or from the light source of the light guide at the interfacesbetween the substrate 85 and turning film 82. Such adhesive may be usedelsewhere as well. Alternative approaches to adhering the layerstogether may also be used.

The plurality of turning features 82 a in the turning film 82 turn lightnormally guided in the light guide 81 such that the light is redirectedtowards the display elements 86 and such that the propagation directionof the turned light forms an angle smaller than 45 degrees from thenormal to the surface of the display elements. Accordingly, light isredirected through the thickness of the light guiding portion 81substantially normal to the light guide and the array of displayelements 86 and is transmitted to the interferometric modulators 86possibly at normal incidence or substantially close thereto. In certainembodiments, the turning features 82 a may comprise a plurality ofsurface features or volume features. In some embodiments, the turningfilm 82 comprises a diffractive optical element and the turning featurescomprise diffractive features extending across the width of the turningfilm 82. The diffractive optical element may comprise volume or surfacefeatures, extending across the width of the turning film 82. In certainembodiments, the turning film 82 comprises a hologram and the turningfeatures 82 a comprise holographic features. The hologram may compriseholographic volume or surface features, extending across the width ofthe turning film 82. The holographic film may be disposed on a plasticcarrier.

Alternatively, the turning features 82 a may comprise a plurality ofmicroprisms extending along the width of the turning film 82. Themicroprisms may be configured to receive light 5 propagating along thewidth of the turning film 82 and turn the light 5 through a large angle,usually between about 70-90°. The prismatic microstructures may comprisetwo or more turning facets angled with respect to one another forreflecting the light via total internal reflection and causing the lightto be turned toward the array of display elements 86 at normal incidenceor near normal incident thereto. The prismatic microstructures may beincluded in a film disposed on a carrier. Note that the size, shape, andseparation of the turning features may vary. A wide variety of othertypes of turning films, diffractive, holographic, prismatic, orotherwise are possible. Accordingly, different sizes, shapes,configuration, and arrangements may be employed.

After being turned by the turning features 82 a, the light 5 istransmitted through the thickness of the light guiding region 81 towardthe interferometric modulators 86 where it may be modulated andreflected back through the light guiding portion 81 towards a viewerdisposed in front of the display device to provide an image on thedisplay device. This reflected light is schematically represented by anarrow 89 in FIG. 8.

In various embodiments, light propagating through the light guidingportion 81 at steep angles (closer to the display elements' normal),such as light turned substantially normal to the light guiding portion81 by the turning film 82, or ambient light, will be transmitted throughthe interfaces between the layers with low reflection. This normallyincident light or near normally incident light preferably looses lessthan about 0.5% of its power or flux, and more preferably looses lessthan about 0.1% of its power or flux.

As described above, in alternative embodiments, the turning film 82 andthe diffuser 84 need not include carriers 82 b, 84 b. For example, thediffuser 84 may comprise a transparent adhesive or other material withlight diffusing or light scattering features such as particulatesinterspersed therein to provide the light diffusing characteristics.This design may further decrease the thickness of the overall displayillumination apparatus 80 by removing the need for a carrier 84 b, whichmay cause the diffuser layer 84 to be between about 25-100 microns thickin some embodiments.

FIG. 9 shows another embodiment of an illumination apparatus 80 of adisplay device. In this embodiment, an anti-reflective layer 90 has beendisposed forward of the diffuser 84. In this particular embodiment, theanti-reflective layer 90 is disposed on the carrier 84 b which supportsthe diffusing layer 84 a. Other embodiments can be configureddifferently. For example, one or more layers may be disposed between thediffuser 84 and the anti-reflective layer 90. Also, the diffuser 84 maybe constructed differently. In some embodiments, for example, asdescribed above, the carrier 84 b may be excluded.

In various embodiments, the anti-reflective layer 90 reduces reflectionof ambient light from the illumination apparatus 80. Such reflectedambient light can decrease the contrast of the device as the viewer seesthe reflected ambient which is un-modulated light together with themodulated light from reflected from the array of light modulators 86.

The anti-reflective layer 90 may comprise one or more layers that reducereflection. The anti-reflective layer 90 may for example be atransparent dielectric that increases index matching between theillumination apparatus 80 (e.g., the diffuser 84) and ambient (or alayer forward the anti-reflective layer). In some embodiments, theanti-reflective layer 90 comprises a multilayer stack such as aninterference stack like a quarter-wave stack. A variety ofanti-reflective layers are possible.

FIG. 9 also illustrates other possible variations in the design of theillumination apparatus 80. A cladding 88 a is shown disposed between theturning film 82 and the diffuser 84. For example, this cladding 88 amay, for example, comprise a material having a lower refractive indexthan that of the turning film 82 and possibly of the substrate 85. Thecladding 88 a may therefore assist in guiding light within the lightpropagation region 81 via total internal reflection. With the lowerindexed cladding 88 a, the refractive index of diffuser 84 a is notlimited to being lower than that of turning film 82. In otherembodiments, the diffuser 84 may form part of the cladding 88 a asdiscussed above with regard to FIG. 8. Other variations are alsopossible.

In the embodiment depicted in FIG. 9, the turning film 82 is attached tothe cladding 88 a. A separate carrier 82 b for supporting the turningfeatures 82 a such as shown in FIG. 8 is not included in FIG. 9 toillustrate variations in possible designs. The substrate 85 or cladding88 a may provide structural support for the turning film 82 or theturning film may be sufficiently rigid itself. In some embodiments, theturning film 82 comprises a prismatic film. In other embodiments, theturning film 82 comprises a diffractive or holographic layer. Stillother variations are possible.

FIG. 10 shows another embodiment of an illumination apparatus 80 of adisplay device. In this embodiment, a cover lens or touch panel 100 hasbeen disposed forward of the diffuser 84. In other embodiments, thecover lens or touch panel 100 may instead comprise a cover plate that isplanar. In this particular embodiment, the cover lens or touch panel 100is disposed on the diffuser 84. Other embodiments can be configureddifferently. For example, one or more layers may be disposed between thediffuser 84 and the cover lens or touch panel 100.

The cover lens 100 may comprise a positive or negative power opticalelement. The cover lens 100 may comprise a refractive lens or adiffractive (e.g. holographic) lens. In some embodiments, a plurality oflenslets may be disposed forward of the diffuser 84.

The touch panel 100 may comprise a wide variety of touch panels thatpermit a user to touch portions of the illumination apparatus 80 ordisplay device to enter data, select options, or control the displaydevice. Touch panels 100 yet to be developed may also be used.

FIG. 10 also illustrates other possible variations in the design of theillumination apparatus 80. For example, in the embodiment depicted inFIG. 10, the diffuser 84 is attached to the cover lens or touch panel100 and carrier 82 b for the turning film 82. A separate carrier 84 bsuch as shown in FIG. 8 and FIG. 9 is not included in FIG. 10 toillustrate variations in possible designs. The cover lens or touch panel100 and carrier 82 b for the turning film 82 may provide structuralsupport for the diffuser 84 or the diffuser may be sufficiently rigiditself. In some embodiments, the diffuser 84 comprises an adhesive, forexample, adhering the cover lens or touch panel 100 to the turning film82. The adhesive may include diffusing features or scatter features suchas particulates therein to diffuse the light. The diffuser 84 may alsocomprise a gel in some embodiments. The gel may include diffusingfeatures or scatter features such as particulates therein to diffuse thelight. The gel may provide optical coupling between the cover lens ortouch panel 100 and the turning film 82 and turning features 82 a. Stillother variations are possible. In various embodiments, scatter featuresare disposed in a material at least a portion of which is a cladding forthe light guide 81. In such embodiments, at least a portion of thematrix material may be disposed between the scattering feature and thelight guide 81. Accordingly, the scattering features may be disposed inthe cladding and at least a portion of the cladding is disposed betweenthe scattering features and the turning film.

FIG. 10 illustrates that a wide variety of components may be added tothe illumination apparatus 80 and/or the display device. In additionanti-reflective layers 90, touch screens and/or lens 100, othercomponents may also be included.

A wide variety of other alternative configurations are also possible.For example, components (e.g., layers) may be added, removed, orrearranged. Similarly, processing and method steps may be added,removed, or reordered. Also, although the terms film and layer have beenused herein, such terms as used herein include film stacks andmultilayers. Such film stacks and multilayers may be adhered to otherstructures using adhesive or may be formed on other structures usingdeposition or in other manners.

Accordingly, although this invention has been disclosed in the contextof certain embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. In addition, while several variations of the invention havebeen shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the invention. It should be understood that various featuresand aspects of the disclosed embodiments can be combined with, orsubstituted for, one another in order to form varying modes of thedisclosed invention. Thus, it is intended that the scope of the presentinvention herein disclosed should not be limited by the particulardisclosed embodiments described above, but should be determined only bya fair reading of the claims that follow.

What is claimed is:
 1. A display system comprising: a plurality ofdisplay elements; a light guide forward the plurality of displayelements, the light guide configured to guide light therein by totalinternal reflection, wherein the light guide includes: an opticallytransmissive plate; and a turning film forward the plate, the turningfilm including a holographic layer configured to turn light guided inthe light guide toward the plurality of display elements; and adiffusing layer forward the light guide.
 2. The display system of claim1, wherein the plate includes glass or plastic.
 3. The display system ofclaim 2, wherein the display elements are formed on the plate.
 4. Thedisplay system of claim 1, wherein the plurality of display elementsinclude electromechanical system structures.
 5. The display system ofclaim 4, wherein the electromechanical system structures include firstand second reflective surfaces, at least one of the first and secondreflective surfaces being movable with respect to the other.
 6. Thedisplay system of claim 5, wherein the plurality of display elementsinclude interferometric modulators.
 7. The display system of claim 1,wherein the holographic layer is disposed on a plastic carrier.
 8. Thedisplay system of claim 1, wherein the diffusing layer has a lower indexof refraction than the holographic layer.
 9. The display system of claim1, wherein the diffusing layer is directly adjacent the turning film ordirectly adhered to the turning film with an adhesive.
 10. The displaysystem of claim 1, wherein the turning film is disposed on a plasticcarrier and the plastic carrier is directly adjacent the diffusinglayer.
 11. The display system of claim 1, wherein the diffusing layer isdisposed on a plastic carrier and the plastic carrier is directlyadjacent the turning film or directly adhered to the turning film withan adhesive.
 12. The display system of claim 1, wherein the diffusinglayer includes a gel.
 13. The display system of claim 1, furthercomprising an anti-reflective coating, the anti-reflective coatingforward the diffusing layer.
 14. The display system of claim 1 , furthercomprising: a processor that is in electrical communication with atleast one of the plurality of display elements, the processor beingconfigured to process image data; and a memory device in electricalcommunication with the processor.
 15. The display system of claim 14,further comprising: a driver circuit configured to send at least onesignal to the at least one of the plurality of display elements.
 16. Thedisplay system of claim 15, further comprising: a controller configuredto send at least a portion of the image data to the driver circuit. 17.The display system of claim 14, further comprising: an image sourcemodule configured to send the image data to the processor.
 18. Thedisplay system of claim 17, wherein the image source module includes atleast one of a receiver, transceiver, and transmitter.
 19. The displaysystem of claim 14, further comprising: an input device configured toreceive input data and to communicate the input data to the processor.20. A display system comprising: a plurality of display elements; meansfor guiding light across the plurality of display elements by totalinternal reflection, the means for guiding light including a holographicmeans for turning light toward the plurality of display elements; meansfor diffusing light disposed forward of the holographic means.
 21. Thedisplay system of claim 20, wherein the light diffusing means includes adiffusing layer.
 22. The display system of claim 20, wherein theholographic means includes a holographic layer.
 23. The display systemof claim 21, wherein the plurality of display elements includeinterferometric modulators.
 24. A method of manufacturing a displaysystem comprising: providing a plurality of display elements; providinga light guide configured to propagate light therein, the light guideincluding a plate and a turning film forward the plate, wherein theturning film includes holographic light-turning features configured toturn light guided in the light guide toward the plurality of displayelements; and providing a diffusing layer forward the turning film. 25.The method of claim 24, wherein providing the plurality of displayelements includes forming an array of interferometric modulatorsrearward the light guide.
 26. The method of claim 24, wherein providingthe turning film includes attaching the turning film directly adjacentto the plate.
 27. The method of claim 24, wherein providing thediffusing layer includes attaching the diffusing layer directly adjacentto the turning film.